Plus i assume there is a landing weight limitation. What is the MLW for a 74 and how much fuel will that be assuming no cargo

If I remember correctly, the MLW depends on wether it's a RR, GE or ER 747.
Tonnes.
The Rolls Royce MLW is 295.7
The General Electrics are 285.7
and the Extended Range ER's are 288.9

Average(ish) empty weights are circa
RR 181.0
GE 181.0
ER 184.0

Plus crew + pantry loads of around 5.0 tonnes

So the maximum fuel tankering option would be in a RR.

Just had a booking change and was told both a 747 and A330 had been used to tanker fuel

If I heard correctly, partial use of the pipeline will be available by early next week

regards
layman

A 747 empty weight is around 190 tonnes. Max landing weight about 285 tonnes (I know it varies). So you could land about 95 tonnes. Keep 30 to fly the aircraft out...which leaves an offload of roughly 65 tonnes.